Neonatal isolation enhances anxiety-like behavior following early-life seizure in rats.
BACKGROUND
Emerging evidence indicates that early adverse experiences result in the maladaptive development of the hypothalamic-pituitary-adrenal (HPA) axis and compromise the developing brain to subsequent neurological insults. Well known that mother-infant interaction plays an important role in early environment stimulation, neonatal isolation (NI) paradigm has been used as an early-life stress model in many relevant studies. Further, the effect of seizure on the developing brain is still not clarified despite more susceptibility to seizures of the developing brain. We had previously demonstrated that NI exacerbates cognitive deficit following early-life seizure. The aim of the current study was to investigate whether NI predisposes the brain to early-life seizure-induced long-term anxiety sequelae.


METHODS
Rats were assigned randomly to the following four groups: (1) normal rearing rats (NR); (2) NI rats that underwent daily separation from their dams from postnatal day 2 (P2) to P9; (3) NR rats suffering lithium-pilocarpine-induced status epilepticus (SE) at P10 (NR+SE); and (4) NI+SE rats. At P60, anxiety-related behavior was evaluated using elevated plus-maze (EPM) test.


RESULTS
SE induced in isolated rats rather than in NR rats produced a decrease in percentage of time spent in open arms, and all rats experiencing NI displayed reduced number of closed arm entries.


CONCLUSIONS
Repetitive brief NI exacerbates anxiety-related behavior in EPM test following early-life SE.
Lai
Ming-Chi
MC
The Graduate Institute of Clinical Medical Sciences, Chang Gung University College of Medicine, Kaohsiung, Taiwan.
Yang
San-Nan
SN
Huang
Li-Tung
LT
D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000209:etiology*; D003345:Corticosterone / Q000378:metabolism; D003346:Corticotropin-Releasing Hormone / Q000502:physiology; D008426:Maternal Deprivation; D018782:Maze Learning; D051381:Rats; D017207:Rats, Sprague-Dawley; D013226:Status Epilepticus / Q000523:psychology*; D013315:Stress, Psychological / Q000150:complications*
D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone